This invention relates to a device for symmetrically opening signatures made up of several sheets and arranging them onto a transport saddle. Devices of this kind are also termed "feeders".
Devices of the general type indicated above are known per se, e.g. from German Pat. No. 1,945,501 and German Patent Publication DE-OS No. 26 31 063.
The first-mentioned device comprises a conveyor which brings in the signatures with their spines lying downstream relatively to the transport direction, and rotatable suction cups, or sets of suction cups, which are spaced apart from one another and act on the signature sheets, said device being characterized in that the conveyor is in the form of a conveyor belt which has a horizontal, or slightly inclined, length moving under the suction cups, or sets of suction cups, and includes grippers arranged to act on the signature spines and hold the free edge of the lower half of an open, or parted, signature. Furthermore, the suction cups, or sets of suction cups, cooperate with barriers of photoelectric light for controlling the suction cups, or sets of suction cups.
A main disadvantage of the prior device briefly described above is that the device itself, being provided with a horizontal, or substantially so, working length for opening the signatures, involves a fairly long construction. As is known, in printing, bookbinding, and the like shops, the available space is always at a premium. Moreover, the above-described device requires a wall-mounted element for holding one half of the signature open at the transition area from the front surface to an inclined surface for returning and loading onto the saddle, said element frequently resulting in the signature half being open with a fairly small radius of partition, whereby said signature, when laid onto the saddle, tends to hold the sheets of the folded signature half open.
In the solution proposed by the cited DE-OS No. 26 31 063, for transporting the signatures, the use of a drum, made up of disk-like elements laid side by side, is provided on the exterior of which drum suction cups, or sets of suction cups, are arranged which are rotatable and spaced mutually apart, their rotation centers lying on an external circumference with respect to the drum. So far, besides replacing the working or signature-opening length, which is substantially horizontal in the cited German patent, with a circular working length, that is with a portion of the circumference of said drum, no additional feature can be identified. From FIG. 1, moreover, which illustrates the feeding of signatures from a stack placed under the drum, it is not clear how the wall-mounted element 14 which prevents the signature sheets from opening by gravity can, in fact, prevent such opening or parting movement, for instance with thin or low substance sheets. In addition, in FIG. 6, an arrangement of suction cups, or sets of suction cups, may be seen which are mutually spaced apart with their axes lying on a circumference inside the drum. In view of the disk form of construction of the drum, it is not clear how the sheets of the half signature laid onto the drum can be opened, since the opening or parting action appears to be hindered by the presence of the drum internal disks. Anyhow this solution, even when limited to opening the sheets of the outer signature halves, has the disadvantage of requiring drums of large diameter, if the height of the signatures usually handled and the increased height that such signatures may have are taken into account.
This solution of providing the signature magazine located below the drum, is extremely inconvenient for the operator.